Slurry type liquid treating apparatus



April 2, 1957 E. M. BATTEY 2,737,373

I SLURRY LIQUID TREATING APPARATUS Filed May 26, 1952 ITIM! SL Y TYPELIQUID TREATING APPARATUS Everett M. liattey, Falls Church, Va.,assignor, by mesne assignments, to the United States of America asrepresented by the Secretary of the Army Application May 26, B52, SerialNo. 290,tl42

1 Claim. (Cl. 210-512) This invention relates to slurry type liquidtreating apparatus and process. More particularly it relates toapparatus and process of this general type wherein a mixture of slurry,liquid to be treated, and reagent is discharged from a central mixingzone or chamber through rotating arms across the outer portion of thetank. in such an apparatus the distributing arms rotate below asuspended slurry blanket, or pool through which a throughput portion ofthe liquid discharged from the arms liows upwardly toward a treatedliquid outlet, Whereas the balance of the liquid discharged from theanus flows inwardly across the bottom of the tank and returns to themixing zone.

in apparatus of this type. the arms. are rotated at a relatively highspeed, and it, has been usual to provide discharge orifices in the armswhich direct the flow vertically downwardly toward the bottom of thetank to avoid disturbance of the blanket; and to continuously sweep thebottom free of deposits. In practice it has been found that the rotationof arms with downwardly discharging orifices has a. marked tendency ofcausing the slurry blanket above the arms to rotate in the samedirection as the arms and at the same speed. This is undesirable andactually nullifies the improved distribution sought by rotation of thearms.

It is an object of this, invention to: provide apparatus and process forcontrolling the speed and. direction of rotation of a slurryblanket'overlyiug rotatable distributing arms.

Another object is to provide means for controlling the speed androtation of: a slurry-blanket which can be adjusted to provide anydesired speed and direction of blanket rotation.

Another object is to provide an. improved distributing arm structure foran apparatus of'the: type mentioned.

Another object of the invention istoprovide a rotatable distributing armdischarging downwardly at an'angle to the vertical to provide atangential velocity component opposite to the; direction of the armrotation.

Another object is to provide a, distributing arm which is rotatableabout a vertical axis and can also be rotated about its own horizontalaxis.

Other objects will become apparent upon consideration of the detaileddescription and of the claim.

It has been the usual opinion of those practicing slurry treatment thatrotation of the slurry: blanket due to rotation of rotatable membersbelow the. blanket. should be suppressed, or at least minimized andvarious. kinds of bafiling devices have been used therefor, or therotating members were circulated. at a very low speed. However, rotationof the slurry; blanket, in and ot itself, is not only permissible butoften desirable, provided the velocity and direction of blanket rotationare controlled. There should be an appreciable relative velocity betweenthe rotation of the arms and the rotation of the blanket when the slurryblanket is rotated in the same direction as the arms. I have also foundthat 2,787,378 Patented Apr. 2, 1957 sometimes it is desirable that theslurry blanket rotate in the opposite direction of the arms. Suchreversal has resulted in considerable improvement in the operation ofthe treating unit, not only with regard to distribution but particularlyin avoidance of local boils in the slurry blanket.

I have discovered that the speed of rotation of the slurry blanket canbe controlled, and that rotation of the slurry blanket can be entirelystopped or its direction reversed, by discharging the slurry from thearms at an angle to the vertical so that. there is a tangential velocitycomponent opposite to the direction of arm rotation. The angle ofdischarge may vary from about 15 to about 45, depending on whether it isdesired to merely slow down the rotation of the blanket, to stop it, orto reverse its direction.

Whether slowing down of the rotation of a slurry blanket rotating in thedirection of the arms, or reversal of the direction of rotation resultsin the best operating conditions depends largely on the quantity andquality of the solids in the slurry, and particularly their settlingcharacteristics, and must be decided from case to case. Other factorsinfluencing the blanket rotation are the velocity of the jets dischargedfrom. the arms, which depends on the speed of rotation of the rotor ofthe apparatus, and the velocity of rotation of the arms, which iscontrolled independently of the speed of rotation of the rotor. Oneditficulty of controlling the slurry blanket rotation is, therefore,that the correct angle of discharge usually can be ascertained onlyafter the apparatus has been put in operation, and that. the angle mustbe changed if the characteristics of the liquid under treatment changeconsiderably. I, therefore, suggest to support the arms in such mannerthat they can be rotated about their horizontal axis and thus can bereadily adjusted to the. angle of discharge which is found best inoperation.

The invention will be more readily understood by reference to thedrawing wherein:

Figure l is a vertical cross-sectional view of an apparatus utilizingthe invention;

Figure 2 is an enlarged vertical cross-sectional view of a distributingarm taken along line 22 of Figure .l; and

Figure 3 is an enlarged vertical sectional view of the adjustable armmounting of Figure 1.

The apparatus shown in Figure lfor purposes of illustrating theinvention is similar to the apparatus. disclosed and claimed in thecopending application of- Wal ter J. Hughes, Serial No. 212,761, filedFebruary 26, 1951, now Patent No. 2,673,181, and no claim is made hereinto this apparatus per se. The present invention is not limited: to use.in connection with this specific apparatus, but can be applied to otherapparatus of the general. type where. liquid is discharged through armsrotating below a slurry blanket. The invention corrects objectionablefeatures of such previously known apparatusand provides. for betteroperation.

The liquid treating apparatus shown in Figure. 1 comprises. a tank 10,which may have. any suitable shape but is shown for purposes ofexemplificationas having a substantially flat bottom 11 and acylindrical boundary wall 12. Treated liquid overflows intoa launder 13and is withdrawn through an efiiuent conduit 1 Snitable means forwithdrawing excess solids are provided and may take the form of a sludgesump 15 in the bottom 11, and a sludge blow-cit line 16 leading from thesump 15.

Axially mounted in the tank 10 is a partition structure 20 comprising anouter partition 21, and an inner partition 22 which may be independentlysupported or, as

shown, he supported from the outer partition 21 as by brackets 23. Thepartitions 21 and 22 may have any suitable configuration, but are shownfor purposes of illustration as tubular. The lower edges of partitions21 and 22 are spacedabove the bottom 11 of the tank, and the channel 24between the partitions is closed at the lower end by a floor 25. Theupper edge of the outer partition 21 is above the overflow into thelaunder 13, and the upper edge of the inner partition is at a lowerelevation, thus providing an overflow from the space within the innerpartition 22 to the channel 24. The lower part of the outer partition isprovided with a plurality of ports 26 symmetrically spaced about thepartition 21.

A rotor 30 is mounted within the partition structure 20, preferably justabove the upper end of the inner partition 22, as shown, and can berotated by means of a suitable motor-reducer 31. To afford mixing of theliquid to be treated with the reagent in the presence of slurry pumpedupwardly through the partition 22 by the rotor 30, the liquid to betreated and the reagent are introduced into the space Within thepartition structure 20 at opposite sides of the rotor 30, as throughconduits 32 and 33, respectively, or the liquid to be treated can beintroduced into the space within the partition 22 below the rotor, asthrough a conduit 32a. The latter construction is preferred when therate of raw water supply varies considerably, as it permits to maintaina constant volume of discharge through the arms 50, and therefore aconstant speed of rotation of the slurry blanket, regardless of the rateof raw water flow.

A plate 35 may be mounted in any suitable manner between the open lowerend of the inner partition 22 and the sump 15 and shelters the sump fromthe turbulence set up by the return flow of slurry to the innerpartition 22.

The outer partition 21 is rotatably supported by any suitable means,such as a channel structure 36 surrounding its upper end and riding onrollers 37 journaled in bearings 38. The bearings 38 are supported froma walkway or beam 39 spanning the tank 10. To prevent sideslipping ofthe channel structure 36 as it travels over the rollers 37, a pluralityof guide rollers 40 are provided and are journaled in bearings 41, whichalso are supported by the beam 39. Any suitable means can be used torotate the partition 21. For purposes of illustration an internal ringgear 42 is shown which meshes with a pinion 43 mounted on the shaft of aspeed reducer 44, driven by a motor 45. The motor 45 and speed reducer44 can be mounted on the beam 39. In Figure 1 it is assumed that thepartition 21 rotates clockwise.

A plurality of hollow distributing arms are equally spaced about thepartition 21 to register with the ports 26. The arms 50 extend from theouter partition 21 across the tank 10 and are in hydraulic communicationwith the channel 24 through the ports 26. Usually at least four arms areused, but in larger tanks six or more arms should be used for gooddistribution. The arms 50 are provided with discharge means 51, whichmay be in the form of a continuous slot, as shown on the right hand armin Figure 1, or of orifices suitably spaced along the length of the arm,as shown on the left hand arm of said figure. As best shown in Figure 2,the discharge opening or openings are located in the lower portion ofthe arm 50 and with their center line C at an angle to the verticalcenter line C of the arm 50 in the direction opposite the direction ofarm rotation indicated by the arrow R.

Since in practice the angle to the vertical may vary considerably, Iprovide means for adjustably mounting the arms 50 on the partition 21.The ports 26 are surrounded by couplings 55, which are welded orotherwise afiixed to the partition 21. Each coupling is machined toprovide a shoulder 56 which serves as a stop for the distributing armwhich is inserted in the coupling 55. Each coupling is tapped at twoplaces which are apart to permit the insertion of set screws 57, whichbear against the arm 50 and hold it fixedly in the selected position. Byloosening the screws 57 the arm 50 can be rotated about its axis in thecoupling 55 until the slots or orifices 51 are in the correct angularposition to obtain the speed and direction of rotation of the slurryblanket desired, and then can be fixed in this position by tighteningthe screws. The angle from the vertical of the center line of thedischarge opening should not be less than about 15 and not more thanabout 45 and will usually be within the range of from 15 to 30. Thechoice of the angle depends on the characteristics of the slurry, thespeed of the rotor 30 which controls the velocity of the jets dischargedfrom the arms 50, and the speed of rotation of the arms 50 which iscontrolled by motor-reducer 45--44.

I claim:

In a slurry type liquid treating apparatus having a tank which duringnormal operation contains a slurry blanket and an overlying body ofclarified liquid, a central mixing chamber surrounded by a casingseparating said mixing chamber from an outer space between said casingand the wall of said tank and conduits having longitudinally aligneddischarging distributing openings connected to apertures in the wall ofsaid casing adjacent the bottom of said tank and extending from saidcasing adjacent to but spaced from the bottom of said tank forapproximately the entire distance of the outer space intermediate saidtank and said casing, the improvement comprising a collar secured tosaid casing in registry with each of said apertures and facing theintermediate space between said casing and said tank, each of saidcollars being dimensioned to surround a conduit, adjustable fasteningmeans carried by each collar for engaging a conduit to maintain it incommunication with an associated aperture, each conduit secured in acollar by said adjustable fastening means to position the openings insaid conduit at preselected vertical angles whereby slurry mixtureconducted to said casing and discharged from said openings fordistribution over the bottom of said tank upon rotation of said casingimparts a substantial tangential velocity to the slurry mixtureunderlying the slurry blanket in said tank and a minimum verticalvelocity to slurry solids traveling upward to the slurry blanket whilesimultaneously controlling the rotational velocity of the slurry blanketrelative to the rotational velocity of the conduits.

References Cited in the tile of this patent UNITED STATES PATENTS806,214 Trent Dec. 5, 1905 1,678,788 Remick July 31, 1928 1,837,191Baldwin Dec. 22, 1931 2,101,908 Joos et a1. Dec. 14, 1937 2,204,093Mallory June 11, 1940 2,245,587 Hughes June 17, 1941 2,259,221 Darby eta1. Oct. 14, 1941 2,525,842 Thompson et a1. Oct. 17, 1950 FOREIGNPATENTS 556,447

Great Britain Oct. 5, 1943

